Cortical mapping is a useful tool in carrying out neurosurgical procedures near “eloquent” brain regions. Such neurosurgical procedures may be performed in a subject suffering from one of a number of diseases. For example, nearly 50 million people worldwide suffer from epilepsy, a chronic neurological disorder. Epilepsy is often successfully treated using medications. However, in a large percentage of cases sufferers do not have control of their seizures. In many cases, surgery to remove the epileptic focus is necessary. Surgical procedures may produce trauma to the patient and run the risk of removing brain areas that are critical to language, sensorimotor, or cognitive function, often resulting in some degree of neurological impairment the patient. As a result, clinicians must map the functionality of the brain tissue prior to resection to ensure that the removal of critical tissue is minimal.
The traditional method for cortical mapping is electrical cortical stimulation (ECS). Using ECS, only one site can be tested at a given time and must often be tested repetitively for confirmation. It may evoke unwanted seizures. And, ECS can misrepresent important information about distributed cortical operations. As a result, patients often have neurologic impairments after surgery despite comprehensive ECS mapping.